Jana Partners' Rosenstein

Despite working in finance for 30 years and amassing a princely fortune, Barry Rosenstein has always been an outsider on Wall Street. After graduating from Lehigh University and Wharton in the early 1980s, he had a hard time getting a job, ending up as an associate in the investment-banking unit at Merrill Lynch, which at the time didn't have the same cachet as Salomon Brothers, Morgan Stanley, or Goldman Sachs. Even at Merrill, the Bruce Springsteen fan from West Orange, N.J., didn't feel like he belonged: A supervisor told him he'd have to stop wearing ventless suits, because that "was not Merrill Lynch's...